As an isolated case, it's too soon to give up on Murphy as a NHL defenseman. He's only 22 and never really had the luxury of proper development in the AHL, mostly due to our lack of depth during the early years of his pro career. He could easily end up being an offensive juggernaut as a defenseman, especially on the power play and a 3-on-3 OT unit.
However, from a GM perspective the right O for D offer might be of interest. Lord knows, JR would have made a run at a young puck-moving offensive defensemen like Murphy, particularly with his right shot on the PP. Protected minutes, no problem.
Taking inventory, we now have on the team and in the pipeline:
LEFT SHOT: Hanifin, Fleury, Slavin, Jordan, Carrick, and Rissanen (plus maybe Lowe), with Liles (UFA) and Hainsey (through '16-17) as veteran plugs
RIGHT SHOT: Faulk, Wisniewski (through '16-17), Murphy, Pesce, Biega, and McKeown
So, if one believes our future D-pairings could be something like this:
Hanifin / Faulk
Fleury / Pesce
Carrick / Murphy or Biega
Jordan or Rissanen / Biega or McKeown
Well, then, yes Murphy might be expendable, especially for a team that needs wingers.